I know this isn't exactly high on Sonic Team Jr.'s priority list, as it doesn't affect the main SRB2 game in any way, but the hardcoded Homing Attack ability can lock onto objects outside of the 2D plane the player character is in if they're in 2D mode, meaning that having enemies shooting at the player from the background in 2D mode (for example) can break the level for characters with that ability. This glitch definitely sounds fixable, as I'm sure the 2D Homing Attack thinker could be reprogrammed to check that the Y position of the target is equal to that of the player character before initiating the attack, but again, this is probably fairly low-priority, so no rush (not like I have control over that kind of thing anyway).

I know this isn't exactly high on Sonic Team Jr.'s priority list, as it doesn't affect the main SRB2 game in any way, but the hardcoded Homing Attack ability can lock onto objects outside of the 2D plane the player character is in if they're in 2D mode, meaning that having enemies shooting at the player from the background in 2D mode (for example) can break the level for characters with that ability. This glitch definitely sounds fixable, as I'm sure the 2D Homing Attack thinker could be reprogrammed to check that the Y position of the target is equal to that of the player character before initiating the attack, but again, this is probably fairly low-priority, so no rush (not like I have control over that kind of thing anyway).

I used to put invisible walls next to the player to stop them going off track in 2d. I've realised this issue before however the homing attack in srb2 has other glitches that should be focused on more (e.g.: the fact that you home-in on anything directly beneath you, the weird anti-gravity glitch; you home upwards). But that's my opinion. For now you might as well rely on invisible fofs or placing the enemies out of (homing attack) reach from the player.